Creosote composition of improved flowability and its production



fl t State m No Drawing. Filed June 10, 1959,.Ser. No. 819,229 7 Claims. (Cl. 167-31) This invention relates to high-boiling hydrocarbon mixtures of improved flow characteristics. In one specific aspect, it relates to creosote, rendered capable of fiowing at lower temperatures, which is more easily handled during commercial use. In another aspect, itrelates toa method of treating creosote to make it readily dischargeable from tank cars and other shipping containers.

Creosote is a distillate of coal tar produced by the high temperature carbonization of bituminous coal. It is a mixture of high-boiling hydrocarbons comprising about 90 percent aromatic compounds having 1-4 fused rings, about percent phenolic compounds, about 3 percent nitrogenous heterocyclic compounds and 2 percent sulfur-containing hydrocarbons. Commercial grade creosote, which is used extensively as a wood preservative, has a continuous boiling range between about 200 and 355 C.; generally not more than 5 percent is distillable at 210 C. and not more than 85 percent or less. than 60 percent is distillable at 355 C.

Creosote is normally liquid at temperatures of about 40 C. At lower temperatures, the higher boiling constituents crystallize out and the creosote becomes a partially solidified mass. When crystal formation occurs, it is difiicult to redissolve the crystals; to do so it is necessary to heat the creosote at high temperatures for a prolonged period of time.

In commercial practice creosote is shipped to the consumer in tank cars equipped with built-in steam coils in order to provide the necessary heat to liquify crystallized creosote and to effect discharge thereof. Creosote is usually charged to the tank car at a temperature of about 75 C. Because of the temperature drop encountered (particularly in cold weather) when creosote is shipped over long distances, it arrives at its destination in a more or less solid state. In order to discharge completely the creosote from the shipping car, it is generally necessary to heat the creosote to a temperature of about 75-80 C. for about -12 hours or more. Since creosote consumers are reluctant, because of the cost of steam involved, to heat the creosoteto that temperature for the length of time required to remove it, large volumes of creosote remain in the car and are returned to the shipping point. This inefficient operation results in considerable monetary loss occasioned by the loss of revenue from the returned creosote, the transportation costs to and from the customer and the expense of cleaning the tank car.

Quite surprisingly, we have discovered a method of treating creosote whereby the flow temperature, i.e. the temperature to which creosote must be heated to obtain suflicient dissolution of the crystalsto permit complete discharge from a tanlt car or container, is reduced approximately l5-30 C. and the required heating time is reduced to the extent of about 50 percent.

It is, therefore, an object of the present invention to Patented June 13, 1961 e CC provide creosote capable of flowing or being discharged from containers at a reduced temperature and in a shorter period of time. It is a further object to provide a method of treating creosote to render it easily dischargeable from tank cars or other containers without adversely affecting the preservative properties of the creosote.

In accordance with the invention, creosote is intimately admixed with about 0.0010.1 percent by weight, based on the weight of the creosote, of a water-soluble polyoxyalkylene condensate, the condensate being characterized by a viscosity of about 5,000-20,000 centipoises at 25 C. of a 1 percent by weight solution of the condensate in water.

The polyoxyalkylene condensate useful in the invention is made by condensing ethylene oxide, propylene oxide, or mixtures thereof to form a high molecular weight ether containing the group --(C H O) OH, wherein n is an integer having a value of 2 or 3 and m is a large whole number. The alkylene oxide may be condensed solely with itself or the polyether chain may be built upon another organic compound such as an amine. While there are many commercially available types of such condensates, only those which are watersoluble and which have a very high molecular weight are useful in the present invention. We have found that the most suitable Way of determining whether a particular condensate is effective is by measuring the viscosity of a one percent by weight solution of the condensate in water at 25 C. The viscosity measurement provides a relative indication of the molecular weight of the condensate. Only those condensates which are characterized by a viscosity of about 5,000-20,000 centipoises at 25 C. of a freshly made one percent solution of the condensate in water are suitable in the invention. A particularly useful polyoxyalkylene condensate is sold by the Union Carbide & Chemical Company under the trade name Polyox Coagulant. Polyox Coagulant is a water-soluble, solid polyethylene oxide condensate having an estimated molecular weight of between about 1 and 10 million and a softening point of 6567 C. A one percent water solution of Polyox Coagulant has a viscosity of 5,500 centipoises and higher at 25 C.

The amount of polyoxyalkylene condensate admixed with the creosote must be carefully controlled. If insuificient condensate is admixed therewith, the creosote will not flow at reduced temperatures. If too large a quantity of condensate is used, it tends to cause gelation of the creosote, thus defeating the purpose of the invention. Generally, the condensate is admixed with creosote in an amount of about 0.001 and 0.1 percent by weight, based on the weight of the creosote. With most creosotes, if more than about 0.1 percent is used, there is a definite tendency toward gelation. However, if the creosote contains a minimum amount of the very high boiling constituents, the condensate may be used in greater amounts without gel formation and the beneficial eifect of the invention is still obtained. Preferably, the amount of condensate in the final creosote ranges between about 0.003 and 0.01 percent by weight.

In accordance with the method of the invention, the condensate is added to creosote in sufiicient amount as an aqueous solution containing between about 0.3 and 3 percent by weight condensate. If the water solution contains more than about 3 percent by weight condensate,

it becomes extremely viscous and is diflicult to admix uniformly with the creosote. The lower limit of condensate concentration in the aqueous solution is governed by practical, rather than theoretical, considerations. If the aqueous solution is too dilute large quantities of water must be added to the creosote to obtain the desired concentrations of condensate therein. The specifications for commercial creosote require that it con- A 1 percent by weight solution of this material in water has a viscosity of 5,500 centipoises and higher at 25 C. as measured by Brookfield viscometer RVF at 2 r.p.m. using a No. 2 spindle. The samples contained varying amounts of condensate and were tested at different temperatures The How properties of each of the treated creosotes were compared with those of an untreated sample. The results are shown hereunder in Table I.

Table 1 Concentration Concentration Deeanta of Condensate of Water in Test 'Iemtion, per- Type of Creosote in Creosote, Creosote, perperature, cent by percent by cent by C. volume weight volume Commercial V 0. 033 2. 3 25 90 0.000 1. a 25 0.0033 1 25 07 0.0000 0 25 5 0.01 3 6 95 0.00 0 6 5 CommercialLaboratory Red led 10 percent creosote crystals 0.0033 1 0 Do 0.0000 0 26 0 0.0033 1 100 0.0000 0 35 10 tain less than about 3 percent by weight Water. The condensate is added in aqueous solution, since it is difiicult to obtain a uniform admixture when solid condensate is used.

The condensate is added to the creosote at a temperature between the temperature at which the creosote is incipiently liquid and the boiling point of the aqueous solution of condensate. Generally, this temperature ranges between and 95 C. Since it is commercial practice to charge the creosote to a tank car or shipping container at a temperature of about C., it is convenient to add the aqueous solution of the condensate during the charging operation. Mixing can be accomplished by pumping the condensate solution into the creosote feed line leading to the tank car. The creosote in the tank car is agitated with air to provide an intimate admixture.

Our invention is further illustrated by the following examples:

EXAMPLE I The following test procedure was established to determine the eifectiveness of the condensate in. improving the flow properties of creosote:

The creosote under test is heated to approximately C. and a measured amount is weighed in a 250 ml. beaker. The desired amount of condensate-water solu tion of required concentration is added thereto and the mixture is agitated with a laboratory mixer for five min.- utes. After agitation, the treated mixture is poured into a graduated cylinder. An untreated portion of the creosote is also poured into a graduated cylinder as a control. After at least 20 hours at a given temperature, each cylinder is inverted and its contents are decanted into a beaker. The amount of material decanted from each cylinder is noted and recorded. If the creosote does not flow from the graduate at the temperature selected, the graduate and its contents are placed in a water bath maintained at an elevated temperature. After a fixed heating period, the decanting procedure is repeated and the temperature is recorded. The amount of material flowing from the graduate is again noted and recorded. If the creosote does not flow at the second temperature, the heating and decanting procedure is repeated at higher temperatures until all of the material flows from the graduate.

Samples of creosote were treated by adding thereto measured quantities of the polyethylene oxide condensate sold commercially as Polyox Coagulant. As we have noted hereabove, Polyox Coagulant is a high molecular weight water-soluble white resin melting at 65-67 C.

It is observed from the data of Table I that creosote, when treated according to the method of the invention, has remarkably improved fiow properties. The creosote used during the tests was modified to provide for variations ordinarily incurred in commercial production. The creosote designated as Commercial contained a higher percentage of high-boiling aromatic materials than did the laboratory redistilled creosote. The data show that treated laboratory redistilled creosote could be substantially removed from its container at a temperature as low as 6 C., a result which did not obtain with the corresponding untreated creosote. The creosote containing 10 percent creosote crystals, which is representative of a commercial creosote having a high percentage of high boiling compounds, had to be heated to a higher temperature (35 C.) in order to effect percent decantation. At this temperature only 10 percent of the untreated sample could be decanted.

EXAMPLE II A plant scale test was made to determine the effectiveness of the present invention under commercial operating conditions. Two clean 10,000 gallon tank cars were charged with commercial creosote from the same storage tank and at the same temperature (75 C.). To one car an aqueous solution, comprising 5 lbs. of Polyox Coagulant in 50 gallons of water, was added to provide a final condensate concentration of 0.005 percent by weight. Air agitation was employed during charging and mixing. The contents of the cars were allowed to cool and were thereafter examined and reheated with steam. The observations made during the test are shown below in Table II.

The cars were then allowed to cool and were sent by rail to another plant. The following observations were made during the heating and unloading operations, which occurred approximately two months after the initial charging:

The data of Tables II and III clearly show the improved flow properties of creosote treated according to the method of the invention. The novel creosote composition of the invention was successfully rendered dischargeable after a 5-hour heating time at a maximum temperature of 60-61 C. In contrast therewith, a crystalline residue from untreated creosote remained in the car after a hour heating period at a maximum temperature of 77 C.

EXAMPLE III A series of tests were made as described in Example I to determine the effectiveness of various condensates in improving the flow properties of a commercial creosote containing percent creosote crystals. The results are shown below in Table IV.

centipoises at 25 C. of a one percent by weight solution of said condensate in water.

3. Creosote having a lower flow temperature comprising creosote intimately admixed with about 0.001-0.1 percent by weight of a water-soluble polyoxyethylene condenate, said condensate being characterized by a viscosity of about 5,000-20,000 centipoises at 25 C. of a one percent by Weight solution of said condensate in water.

4. Creosote having a lower flow temperature comprising creosote intimately admixed with about 0.003- 0.01 percent by weight of a water-soluble polyoxyethylene condensate, said condensate being characterized by a viscosity of about 5,00020,000 centipoises at 25 C. of a one percent by weight solution of said condensate in water and a melting point of 67 C.

5. Method of lowering the flow temperature of creosote comprising intimately admixing with creosote an aqueous solution containing between about 0.03 and 3 percent by weight of a polyoxyethylene condensate, said condensate being characterized by a Viscosity of about 5,000-20,000 centipoises at 25 C. of a one percent by weight Solution of said condensate in water, in an amount of at least about 0.001 percent by weight and less than that which causes gelation of said creosote.

6. Method of rendering creosote readily dischargeable from containers comprising intimately admixing with creosote about 0.001-0.1 percent by weight of a polyoxyethylene condensate, said condensate being characterized by a viscosity of about 5,00020,000 centipoises at 25 C. of a one percent by weight solution of said condensate in water, as an aqueous solution containing between 0.03 and 3.0 percent by weight of said condensate.

Table IV 00nd nsate Control Tetronic Polyol 2 Polyox e 908 O-1860i-G" Ooagulan Estimated Molecular Weight of (l n densatlz flh 27, 000 20, 000-40, 000 1-10 million Viscosi of a 1 ercen y we g so u ion 0 cond r isate in w ter, centipoises 0. 8 0. 8 14, 00046, 000

Concentration of condensate percent by weight 0. 0065 0. 8 0. 0065 5. 5 Percent Water in Oreosote.-. 0. 7 1. 2 0. 7 1. 2 0. 7 Results, percent by volume, decanted at:

1 A solid condensate of ethylene diamine with ethylene oxide and propylene oxide having a melting point of 1 liquid condensate containing condensed propylene oxide.

It is seen from the data that only the high molecular weight (as determined by the viscosity test) polyoxyalkylene condensates are efiective for purposes of the invention.

We claim:

1. Creosote containing a polyoxyalkylene condensate, said condensate being characterized by a viscosity of about 5,000-20,000 centipoises at 25 C. of a one percent by weight solution of said condensate in Water, in an amount of at least about 0.001 percent by weight and less than that which causes gelation of the creosote.

2. Creosote containing about 0.001-0.1 percent by weight of a polyoxyalkylene condensate, said condensate being characterized by a viscosity of about 5,00020,000

References Cited in the file of this patent UNITED STATES PATENTS 2,904,467 Behr Sept. 15, 1959 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 2,988,477 June 13, 1961 James Beaumont et a1.

It is hereby certified that erro ent requiring correction and that t corrected below.

r appears in the above numbered pathe said Letters Patent. should read as Column 6', line 2O for polyoxyethylene" read polyoxyal'kylene I Signed and sealed this 5th day of December 1961*.

' (SEAL) Attest:

ERNEST W. SWIDER DAVID L. LADD Attesting Officer Commissioner of Patents USCOMM-DC 

1. CREOSOTE CONTAINING A POLYOXYALKYLENE CONDENSATE, SAID CONDENSATE BEING CHARACTERIZED BY A VISCOSITY OF ABOUT 5,000-20,000 CENTIPOISES AT 25*C. OF A ONE PERCENT BY WEIGHT SOLUTION OF SAID CONDENSATE IN WATER, IN AN AMOUNT OF AT LEAST ABOUT 0.001 PERCENT BY WEIGHT AND LESS THAN THAT WHICH CAUSES GELATION OF THE CREOSOTE.
 5. METHOD OF LOWERING THE FLOW TEMPERATURE OF CREOSOTE COMPRISING INTIMATELY ADMIXING WITH CREOSOTE AN AQUEOUS SOLUTION CONTAINING BETWEEN ABOUT 0.03 AND 3 PERCENT BY WEIGHT OF A POLYOXYETHYLENE CONDENSATE, SAID CONDENSATE BEING CHARACTERIZED BY A VISCOSITY OF ABOUT 5,000-20,000 CENTIPOISES AT 25*C. OF A ONE PERCENT BY WEIGHT SOLUTION OF SAID CONDENSATE IN WATER, IN AN AMOUNT OF AT LEAST ABOUT 0.001 PERCENT BY WEIGHT AND LESS THAN THAT WHICH CAUSES GELATION OF SAID CREOSOTE. 